In numerous technical fields, such as the fields of perfumery, cosmetics, or even pharmacy, for example, it is known to use a fluid dispenser in the form of a receptacle associated with a pump or a valve fastened on the opening of the receptacle. By actuating the pump or the valve, fluid is dispensed, optionally in measured out quantities or “doses”. In that type of fluid dispenser, it is essential for the pump or the valve to be fastened in stable and leaktight manner on the opening of the receptacle. To do that, a fastener device is conventionally used which holds the pump or the valve, and which is provided with fastener means for fastening onto the opening of the receptacle. The fastener means can use various techniques, such as screw-engagement, clamping, adhesive, or even snap-fastening or hook-engagement techniques.
A well known embodiment for a fastener device uses a fastener ring comprising fastener means for fastening onto the receptacle neck, and a covering hoop that is engaged axially from top to bottom around the ring. In the present invention, the covering hoop includes hook means co-operating with abutment means formed by the ring for acting together to define axial retainer means for retaining the hoop on the ring. Document EP 1 270 434 describes a fastener device of that type in which the bottom end of the hoop is upturned inwards so as to define an upwardly-directed inner shoulder. The inner shoulder is designed to become engaged below the fastener ring which forms abutment means at this location. In that prior-art document, the axial retainer means for retaining the hoop on the ring are therefore defined by the inner shoulder of the upturned end of the hoop co-operating with the bottom end of the ring, or more precisely with the end edge of the fastener ring. The inner shoulder of the hoop is perfectly annular, so as to define a circle that extends in a single plane. The same applies for the bottom end of the fastener ring, which also defines a circle extending in a single plane. Thus, the engagement of the inner shoulder just below the bottom end of the ring defines a single axial blocking position for the hoop on the ring. Consequently, the engagement or axial abutment of the hoop relative to the ring is imposed by the inner shoulder of the hoop and by the bottom end of the fastener ring, which both extend in planes that coincide while the shoulder comes into abutment contact with the ring.
The drawback with the fastener device of document EP 1 270 434 is that there is no freedom or modularity in axially positioning the hoop relative to the ring. It is sometimes useful for the hoop to be disposed axially relative to the ring as a function of the configuration of the receptacle on which the fastener device is to be mounted. More precisely, the bottom end of the hoop must generally come to bear against the receptacle, so as to create a sort of continuity between the receptacle and the fastener device. Consequently, it is sometimes necessary to push the hoop onto the ring to a greater or lesser extent, which amounts to modifying the axial position of the hoop on the ring.